code: def _update_env_vars(env_vars: dict) -> dict:
      """Placeholder docstring"""
      updated_env_vars = {}
      updated_env_vars.update(_DEFAULT_ENV_VARS)
      if env_vars:
          updated_env_vars.update(env_vars)
      return updated_env_vars
  
file_path: sagemaker-python-sdk/src/sagemaker/serve/model_server/djl_serving/server.py
imports: from __future__ import absolute_import
  import requests
  import logging
  from pathlib import Path
  from docker.types import DeviceRequest
  from sagemaker import Session, fw_utils
  from sagemaker.serve.utils.exceptions import LocalModelInvocationException
  from sagemaker.base_predictor import PredictorBase
  from sagemaker.s3_utils import determine_bucket_and_prefix, parse_s3_url, s3_path_join
  from sagemaker.s3 import S3Uploader
  from sagemaker.local.utils import get_docker_host
label_desc: Use image node_id 1 for calling a global function with example usage: _update_env_vars(env_vars) and returns: updated_env_vars